Information recording processing device, information reproduction processing device, information recording medium and method, and computer program

ABSTRACT

A device, a medium, and a method for recording and reproducing additional data difficult to analyze on an information recording medium are provided. When additional data is recorded onto the information recording medium, or additional data such for example as key information applied to a content decryption process, key generating information, content reproduction control information, or copy control information is recorded on the information recording medium, the parity of data of a recording frame in which to insert the additional data is calculated, and the value of a DC control bit in the frame in which to store the additional data is determined and set on the basis of information indicating whether the parity is even parity or odd parity and the bit value information [ 0 ] or [ 1 ] of the additional data. At a time of reproduction, the constituent bit [ 0 ] or [ 1 ] of the additional data is obtained by only detecting the parity of the recording frame.

TECHNICAL FIELD

The present invention relates to an information recording processingdevice, an information reproduction processing device, an informationrecording medium and a method, and a computer program. Moreparticularly, the present invention relates to an information recordingprocessing device, an information reproduction processing device, aninformation recording medium and a method, and a computer program thatmake it possible to record and read additional information, or variousadditional information such for example as key information applied to acontent decryption process, content reproduction control information, orcopy control information on an information recording medium on whichcontents such for example as image data and music data are recorded in amode difficult to analyze by controlling the setting of DC control bits.

BACKGROUND ART

When data such as music data, image data and the like is recorded asdigital data onto a recording medium, a recording process is performedaccording to a predetermined recording format. For example, an errordetecting/correcting code is added to original data to be recorded, andthe data is converted (coding) into a format corresponding to a specificdata recording and reproduction process and then recorded.

A system has recently been developed which records and reproducesinformation using a blue laser as an information recording mediumallowing high-density information recording. In an information recordingprocess using this blue laser, a modulating process is performed whichbasically modulates two-bit data into three-bit data.

There are movies, music data and the like as contents stored on such aninformation recording medium. A distribution right or the like to manycontents such as music data, image data and the like is generally heldby a creator or a seller of the contents. Thus, generally, indistributing these contents, a certain use limitation is set, that is,only authorized users are permitted to use the contents so thatunauthorized copying or the like is prevented.

Data of one to several movies, for example, can be recorded on a singlehigh-capacity type recording medium such for example as a recordingmedium using a blue laser recording system allowing high-capacityrecording. As contents can be thus recorded easily as digitalinformation, a problem of a flood of unauthorized copies frequentlyoccurs, and therefore a problem of impaired interests of holders ofcontent copyrights and distribution rights is becoming more serious.Because of such a present situation, prevention of unauthorized copyingand protection of interests of holders of content copyrights anddistribution rights are an important challenge.

In order to prevent such unauthorized use of contents, a constitution isproposed in which contents stored on an information recording medium arerecorded as encrypted contents, and encryption key information appliedto use of the encrypted contents, information necessary to generate anencryption key, or various control information for content reproductioncontrol, copy control and the like is stored as secret information onthe information recording medium. A reproduction processing programexecuted in a reproducing device of a user reads secret information suchas a key or the like corresponding to contents to be reproduced,decrypts the contents according to the read secret information, andallows the contents to be used according to reproduction controlinformation.

As a conventional technique in which a secret information embeddingprocess constitution is disclosed (see Japanese Patent Laid-open No.2003-451487 as Patent Document 1), for example, discloses a constitutionthat embeds special data by using connection bits (margin bits) of EFMmodulated data. Japanese Patent Laid-open No. 2002-367282 as PatentDocument 2 discloses a constitution in which a plurality of conversiontables are applied in a modulating process, and at a time ofreproduction, data on a conversion table applied in modulation isextracted and additional data is obtained on the basis of the extracteddata.

However, when information indicating where such an encryption key orcontrol information is stored on an information recording medium isobtained by a user or an unauthorized contents user, the additionalinformation can be leaked or altered. For example, a problem ofalteration of reproduction control information and copy controlinformation or leakage of key information occurs. When key informationis leaked or control information is altered, a form of use of contentswhich form is based on legitimate rights to use the contents collapses,and copyrights and distribution rights of the contents are not fullyprotected.

DISCLOSURE OF INVENTION

The present invention has been made in view of the above problems, andit is an object of the present invention to provide an informationrecording processing device, an information reproduction processingdevice, an information recording medium and a method, and a computerprogram that make it possible to record various information such forexample as an encryption key, encryption key generating information,content reproduction control information, content copy controlinformation, or other content attribute information stored on arecording medium together with contents in a mode that makes itimpossible to read the additional information by a general data readingprocess, and make unauthorized data reading difficult.

According to a first aspect of the present invention, there is providedan information recording processing device characterized by including: amodulated data generating unit for generating a modulated recordingframe by setting a DC control bit in data to be recorded and performingdata modulation processing; and a DC control bit specifying unit fordetermining a bit value of the DC control bit set in a recording framein which to store additional data on a basis of a constituent bit valueof the additional data and a data state of constituent data of therecording frame.

Further, in an embodiment of the information recording processing deviceaccording to the present invention, the data state of the constituentdata of the recording frame in which to store the additional data is astate of whether parity of the constituent data of the recording frameis even parity or odd parity, and the DC control bit specifying unitdetermines the bit value of the DC control bit set in the recordingframe on a basis of two conditions of whether the constituent bit valueof the additional data is zero or one and whether the parity of theconstituent data of the recording frame is even parity or odd parity.

Further, in an embodiment of the information recording processing deviceaccording to the present invention, the DC control bit specifying unitdetermines whether to set total parity of all DC control bits set in therecording frame in which to store the additional data to even parity orto odd parity on a basis of the constituent bit value of the additionaldata and the data state of the constituent data of the recording framein which to store the additional data.

Further, in an embodiment of the information recording processing deviceaccording to the present invention, the information recording processingdevice sets the additional data as constituent information of at leastone of encryption key information, encryption key generatinginformation, content reproduction control information, and content copycontrol information for contents stored on the information recordingmedium.

Further, in an embodiment of the information recording processing deviceaccording to the present invention, the modulated data generating unitgenerates the modulated recording frame by performing a data conversionprocess satisfying RLL (1, 7) as a run length rule.

Further, in an embodiment of the information recording processing deviceaccording to the present invention, the modulated data generating unitperforms a modulated recording frame generating process including aprocess of conversion of two-bit information into three-bit information.

Further, according to a second aspect of the present invention, there isprovided an information reproduction processing device for reproducinginformation stored on an information recording medium, the informationreproduction processing device characterized by including: ademodulating unit for demodulating data read from the informationrecording medium; and an additional data decoding unit for calculating astate of recorded data, and obtaining constituent bit information ofadditional data as recorded information stored in an additional datarecording area on a basis of a result of calculating the state.

Further, in an embodiment of the information reproduction processingdevice according to the present invention, the state of the recordeddata, the state being calculated by the additional data decoding unit,is parity of constituent data of a modulated recording framecorresponding to the additional data recording area, and whether aconstituent bit value of the additional data is zero or one isdetermined on a basis of the state of whether the parity is even parityor odd parity.

Further, in an embodiment of the information reproduction processingdevice according to the present invention, the information reproductionprocessing device generates at least one of encryption key information,encryption key generating information, content reproduction controlinformation, and content copy control information for contents stored onthe information recording medium on a basis of the obtained constituentbit information of the additional data.

Further, according to a third aspect of the present invention, there isprovided an information recording medium characterized in that arecording frame corresponding to an additional data recording area is arecording frame in which a DC control bit having a bit value determinedon a basis of two conditions of a constituent bit value of additionaldata and whether parity of constituent data of the recording frame iseven parity or odd parity is set, and data based on the recording frameis recorded on the information recording medium.

Further, in an embodiment of the information recording medium accordingto the present invention, the recording frame corresponding to theadditional data recording area is recorded with total parity of DCcontrol bits set to one of even parity and odd parity according to apredetermined rule on a basis of a correspondence between theconstituent bit value of the additional data and a data state of theconstituent data of the recording frame in which to store the additionaldata.

Further, in an embodiment of the information recording medium accordingto the present invention, the information recording medium stores theadditional data as constituent information of at least one of encryptionkey information, encryption key generating information, contentreproduction control information, and content copy control informationfor contents stored on the information recording medium.

Further, in an embodiment of the information recording medium accordingto the present invention, the data based on a modulated recording framegenerated by performing a data conversion process satisfying RLL (1, 7)as a run length rule is recorded on the information recording medium.

Further, in an embodiment of the information recording medium accordingto the present invention, the data based on a modulated recording framegenerated by performing a process of converting two-bit information intothree-bit information is recorded on the information recording medium.

Further, according to a fourth aspect of the present invention, there isprovided an information recording processing method characterized byincluding: a DC control bit specifying step of determining a bit valueof a DC control bit set in a recording frame in which to storeadditional data on a basis of a constituent bit value of the additionaldata and a data state of constituent data of the recording frame; and amodulated data generating step of generating a modulated recording frameby setting the DC control bit specified in the DC control bit specifyingstep in data to be recorded and performing data modulation processing.

Further, in an embodiment of the information recording processing methodaccording to the present invention, the data state of the constituentdata of the recording frame in which to store the additional data is astate of whether parity of the constituent data of the recording frameis even parity or odd parity, and the DC control bit specifying stepincludes a step of determining the bit value of the DC control bit setin the recording frame on a basis of two conditions of whether theconstituent bit value of the additional data is zero or one and whetherthe parity of the constituent data of the recording frame is even parityor odd parity.

Further, in an embodiment of the information recording processing methodaccording to the present invention, the DC control bit specifying stepincludes a step of determining whether to set total parity of all DCcontrol bits set in the recording frame in which to store the additionaldata to even parity or to odd parity on a basis of the constituent bitvalue of the additional data and the data state of the constituent dataof the recording frame in which to store the additional data.

Further, in an embodiment of the information recording processing methodaccording to the present invention, the additional data is constituentinformation of at least one of encryption key information, encryptionkey generating information, content reproduction control information,and content copy control information for contents stored on theinformation recording medium.

Further, in an embodiment of the information recording processing methodaccording to the present invention, the modulated data generating stepgenerates the modulated recording frame by performing a data conversionprocess satisfying RLL (1, 7) as a run length rule.

Further, in an embodiment of the information recording processing methodaccording to the present invention, the modulated data generating stepperforms a modulated recording frame generating process including aprocess of conversion of two-bit information into three-bit information.

Further, according to a fifth aspect of the present invention, there isprovided an information reproduction processing method for reproducinginformation stored on an information recording medium, the informationreproduction processing method characterized by including: ademodulating step of demodulating data read from the informationrecording medium; and an additional data decoding step of calculating astate of recorded data, and obtaining constituent bit information ofadditional data as recorded information stored in an additional datarecording area on a basis of a result of calculating the state.

Further, in an embodiment of the information reproduction processingmethod according to the present invention, the additional data decodingstep includes a step of calculating parity of constituent data of amodulated recording frame corresponding to the additional data recordingarea as the state of the recorded data, and determining whether aconstituent bit value of the additional data is zero or one on a basisof the state of whether the parity is even parity or odd parity.

Further, in an embodiment of the information reproduction processingmethod according to the present invention, the information reproductionprocessing method further includes a step of generating at least one ofencryption key information, encryption key generating information,content reproduction control information, and content copy controlinformation for contents stored on the information recording medium on abasis of the obtained constituent bit information of the additionaldata.

Further, according to a sixth aspect of the present invention, there isprovided a computer program for performing an information recordingprocess, the computer program characterized by including: a DC controlbit specifying step of determining a bit value of a DC control bit setin a recording frame in which to store additional data on a basis of aconstituent bit value of the additional data and a data state ofconstituent data of the recording frame; and a modulated data generatingstep of generating a modulated recording frame by setting the DC controlbit specified in the DC control bit specifying step in data to berecorded and performing data modulation processing.

Further, according to a seventh aspect of the present invention, thereis provided a computer program for reproducing information stored on aninformation recording medium, the computer program characterized byincluding: a demodulating step of demodulating data read from theinformation recording medium; and an additional data decoding step ofcalculating a state of recorded data, and obtaining constituent bitinformation of additional data as recorded information stored in anadditional data recording area on a basis of a result of calculating thestate.

The computer programs according to the present invention can for examplebe provided to a computer system capable of executing various programcodes by a storage medium provided in a computer readable form, or acommunicating medium, for example a recording medium such as a CD, anFD, an MO or the like, or a communicating medium such as a network orthe like. By providing such a program in a computer readable form, aprocess in accordance with the program is realized on the computersystem.

Other and further objects, features, and advantages of the presentinvention will become apparent from more detailed description on thebasis of accompanying drawings and embodiments of the present inventionto be described later. It is to be noted that a system in the presentspecification is a logical set configuration of a plurality of devices,and that each constituent device is not necessarily within an identicalcasing.

According to a constitution of the present invention, in a recordingprocessing device that records additional data onto an informationrecording medium, or records various additional data such for example askey information applied to a content decrypting process, key generatinginformation, content reproduction control information, or copy controlinformation onto the information recording medium, the value of a DCcontrol bit embedded in a recording frame is determined and setaccording to a state of a data area corresponding to an additional dataembedding area and a bit value [0] or [1] as constituent bit informationof additional data. At a time of reproduction, a reproducing device canobtain the additional constituent bit information [0] or [1] bydetecting the data state of constituent data of the recording frame.With this constitution, additional information such for example as keyinformation applied to a content decrypting process, key generatinginformation, content reproduction control information, or copy controlinformation is embedded in a mode difficult to analyze, and reliablyread at a time of reproduction.

In addition, according to a constitution of the present invention, in aprocess of recording additional data, on the basis of a data state ofwhether parity of data of a recording frame in which to insert theadditional data is even parity or odd parity and bit value information[0] or [1] of the additional data, the constituent bit [0] or [1] of theadditional data can be recorded by only determining and setting thevalue of a DC control bit of the frame in which to store the additionaldata. At a time of reproduction, the additional information can beobtained by only detecting the parity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a configuration of an information recordingprocessing device according to the present invention;

FIGS. 2A, 2B, 2C, and 2D are diagrams (1) of assistance in explainingdetails of processing of a modulated data generating unit in theinformation recording processing device according to the presentinvention;

FIGS. 3D, 3E, 3F, 3G, and 3H are diagrams (2) of assistance inexplaining details of processing of the modulated data generating unitin the information recording processing device according to the presentinvention;

FIG. 4 is a diagram of assistance in explaining a data composition of aconversion table applied in a modulation process of the informationrecording processing device according to the present invention;

FIGS. 5A, 5B, and 5C are diagrams of assistance in explaining details ofprocessing performed in a recording signal processing circuit in theinformation recording processing device according to the presentinvention;

FIGS. 6A, 6B, and 6C are diagrams of assistance in explaining an exampleof a process of setting DC control bits on the basis of additional datawhich process is performed in the information recording processingdevice according to the present invention;

FIGS. 7A, 7B, and 7C are diagrams of assistance in explaining an exampleof a process of setting DC control bits on the basis of additional datawhich process is performed in the present invention;

FIG. 8 is a diagram of assistance in explaining a rule for the processof setting DC control bits on the basis of additional data which processis performed in the present invention;

FIG. 9 is a flowchart of assistance in explaining an additional datarecording process sequence performed in the information recordingprocessing device according to the present invention;

FIG. 10 is a diagram showing a configuration of an informationreproduction processing device according to the present invention; and

FIG. 11 is a flowchart of assistance in explaining an additional datareading and data reproduction process sequence performed in theinformation reproduction processing device according to the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

An information recording processing device, an information reproductionprocessing device, an information recording medium, and a method, and acomputer program according to the present invention will hereinafter bedescribed in detail with reference to the drawings.

The configuration and processing of the information recording processingdevice according to the present invention will first be described withreference to FIG. 1. It is to be noted that the information recordingprocessing device to be described in the following includes a masteringdevice as a device for manufacturing an original disk referred to as aso-called master disk, and further includes a DVD recording andreproducing device and a device having an information recording mediumdrive, such as a PC or the like, which devices are usable by a generaluser. That is, the information recording processing device includesinformation processing devices that can write data not only to masterdisks but also to various recordable or rewritable information recordingmedia.

The configuration and processing of the information recording processingdevice will be described with reference to FIG. 1. The informationrecording processing device includes: an information recording medium101 on which data can be recorded; a pickup 102 for outputting a datarecording signal to the information recording medium 101; a spindlemotor 103 for driving the information recording medium 101; a servocircuit 104 for controlling the pickup 102 and the spindle motor 103; anadditional data error correction coding unit 105; a main data errorcorrection coding unit 106; an additional data recording areacontrolling unit 107; a switch 108; a modulated data generating unit109; DC control bit specifying means 110; and a recording signalprocessing circuit 111.

Content data to be recorded on the information recording medium 101 isencrypted content data, for example. The content data is input as maindata to the main data error correction coding unit 106. The main dataerror correction coding unit 106 performs a coding process of generatingan error correcting code and adding the error correcting code to theinput data.

Thereafter the modulated data generating unit 109 performs a modulatingprocess. The information recording processing device according to thepresent invention performs modulation based on an RLL (1, 7) modulationsystem for basically modulating two-bit data into three-bit data.

The modulation based on the RLL (1, 7) modulation system is a dataconversion system for providing modulated data in accordance with an RLL(1, 7) run length limitation in which data the number of consecutive [0]bits after the modulation is in a range of a minimum of one to a maximumof seven. Incidentally, a conversion table is used in this conversionprocess. A concrete example of use of a conversion table will bedescribed later.

A recording unit referred to as a recording frame in which asynchronizing signal is set is generated on the basis of the modulateddata, and recorded onto the information recording medium 101 via therecording signal processing circuit 111.

The modulating process is performed after a DC control bit [0] or [1] isselected and inserted at certain intervals of the input main data so asto reduce an absolute value of DSV (Digital Sum Variation) at the timeof modulation.

However, in the present invention, in setting a DC control bit in anadditional data recording area, a DC control bit [0] or [1] is selectedand inserted on the basis of a constituent bit of additional data,instead of bit selection according to the above rule. This process willbe described later.

The digital sum variation (DSV) is an index of a DC balance of an NRZIconverted signal generated as a recording signal to be recorded on theinformation recording medium. Specifically, with the DSV as a valueobtained by accumulating bits [0] in a recording bit sequence (NRZIconverted signal) as [−1] and bits [1] in the recording bit sequence(NRZI converted signal) as [+1], the modulating process is performedafter a DC control bit [0] or [1] is selected and inserted so as toreduce a deviation of the DSV from zero. Incidentally, an NRZIconversion process will be described later in detail.

Incidentally, in the configuration according to the present invention,in setting a DC control bit in an additional data recording area, a DCcontrol bit [0] or [1] is selected and inserted on the basis of aconstituent bit of additional data, instead of bit selection accordingto the above rule. This process will be described later.

A modulated data generating process performed in the modulated datagenerating unit 109 will be described in detail with reference to FIG. 2and FIG. 3.

As shown in FIG. 2A, recording data is formed by user data 201 and usercontrol data (UCD) 211. The user data 201 includes entity data of datato be reproduced such as contents or the like. The user control data(UCD) 211 includes various control data such as reproduction controlinformation and the like.

The user data 201 is set as a unit of 32 frames of 2048-byte data andfour-byte parity. The user control data (UCD) 211 is formed by 32 unitsof 18-byte data.

A data block 202 is formed on the basis of the user data 201 of 32frames×(2048+4) bytes. The data block 202 has an arrangement of 304columns×216 rows. Incidentally, one column×one row stores one-byte(eight-bit) data.

An LDC block 203 is generated as a data block obtained by adding 32-rowparity to each column of the data block 202. An LDC cluster 204 of 152columns×496 rows is generated by subjecting the LDC block 203 to aninterleaving process.

The user control data (UCD) 211 is combined with physical address data221 of 16×9 bytes, whereby an access block 212 of 24 columns×30 rows isgenerated. A BIS block 213 is generated as a data block obtained byadding 32-row parity to each column of the access block 212. A BIScluster 214 of three columns×496 rows is generated by subjecting the BISblock 213 to an interleaving process.

FIG. 3D shows the same data as in FIG. 2D, that is, the LDC cluster 204of 152 columns×496 rows generated on the basis of the user data 201 andthe BIS cluster 214 of three columns×496 rows generated on the basis ofthe user control data (UCD) 211.

As shown in FIG. 3D, the LDC cluster 204 of 152 columns×496 rows isdivided into four parts (I to IV) as units of 32 columns, and the BIScluster 214 of three columns×496 rows is divided into three parts (i toiii) as units of one column. These parts are alternately combined witheach other, whereby an ECC cluster 231 of 155 columns×496 rows shown inFIG. 3E is generated.

Further, the ECC cluster 231 is set as a cluster 232 divided into 28parts 0 to 27 as shown in FIG. 3F. Only the part 0 is 25 bits, and theother parts 1 to 27 are 45 bits. Incidentally, the number of bits shownin FIG. 3F is the number of bits per row.

Further, as shown in FIG. 3G, 20 synchronizing (Sync) bits are set. Inaddition, one DC control bit is set between the parts 0 to 27 of FIG.3F.

As a result, a physical cluster 233 of [1240+20 (Sync)+(one DCcontrol×28)=1288]×496 rows is set. Each row of the physical cluster 233is a recording frame 234 as a modulated data generating process unit.

Incidentally, the DC control bits are an index of a DC balance of anNRZI converted signal generated as a recording signal to be recorded onthe information recording medium. Specifically, with DSV as a valueobtained by accumulating bits [0] in a recording bit sequence (NRZIconverted signal) as [−1] and bits [1] in the recording bit sequence(NRZI converted signal) as [+1], a DC control bit [0] or [1] is selectedand inserted so as to reduce a deviation of the DSV from zero.

However, as described above, in the present invention, in setting a DCcontrol bit in an additional data recording area, a DC control bit [0]or [1] is selected and inserted on the basis of a constituent bit ofadditional data, instead of bit selection according to the above rule.This process will be described later.

Returning to FIG. 3, description of the modulated data generatingprocess will be continued. The recording frame 234 formed by 1288-bitdata is subjected to a modulation process for converting two-bit datainto three-bit data. In this data conversion, RLL (1, 7) data conversionis performed to provide modulated data in accordance with a run lengthlimitation in which data the number of consecutive [0] bits is in arange of a minimum of one to a maximum of seven, whereby a modulatedrecording frame 235 is generated.

The modulated recording frame 235 is formed by a total of 1932 channelbits as modulated data bits, that is, 30 synchronizing (Sync) channelbits and (1288−20 sync bits×⅔)=1902 channel bits.

A conversion table is used in the process of data modulation from twobits to three bits in accordance with an RLL (1, 7) run length rule. Aconcrete example of a conversion table is shown in FIG. 4.

As shown in FIG. 4, the conversion table is constructed as a tableassociating modulated data bits with input bits. When input data is[00000000], for example, modulated data bits are [010100100100]. In acase of input data of [11], modulated data bits are [000] when precedingmodulated data bits are [xx1], and modulated data bits are [101] whenpreceding modulated data bits are [xx0].

Modulated data bits in accordance with the RLL (1, 7) run length ruleare generated by performing data conversion from two bits to three bitsaccording to this table.

Returning to FIG. 1, description of the configuration and processing ofthe information recording processing device according to the presentinvention will be continued. The modulated data generating processdescribed with reference to FIGS. 2A to 4 is performed in the modulateddata generating unit 109 in FIG. 1, and a recording signal based on thegenerated modulated data is generated in the recording signal processingcircuit 111.

The recording signal processing circuit 111 generates an NRZI (NonReturn to Zero Inverted) signal whose pulse polarity is invertedaccording to a value [0] or [1] of the modulated data generated by themodulated data generating unit 109. This signal is recorded as arecording signal onto the information recording medium 101.

FIG. 5 shows a configuration for a process of generating an NRZI as arecording signal which process is performed in the recording signalprocessing circuit 111. Channel bits as modulated data bits output fromthe modulated data generating unit 109 is input to the recording signalprocessing circuit 111 including NRZ converting means 121, exclusive ORmeans (XOR) 122, and delaying means 123. FIG. 5A shows channel bits;FIG. 5B shows an output signal from the NRZ converting means 121; andFIG. 5C shows NRZI converted pulses, which are a recording signal as afinal output of the recording signal processing circuit 111. Thisrecording signal is output to the pickup 102, so that the recordinginformation is recorded onto the information recording medium 101 undercontrol of the servo circuit 104.

In the case of a recording frame corresponding to an additional datarecording area, the constitution of the present invention determineswhether to set a DC control bit (see FIG. 3G) to [0] or whether to setthe DC control bit to [1], which setting is made in the modulated datagenerating unit 109, on the basis of a constituent bit of additionaldata.

For example, a specific recording frame is selected as an additionaldata recording area, and a DC control bit in the selected recordingframe is selected to be [0] or [1] on the basis of a constituent bit ofadditional data. This process enables the additional data to be assignedto the modulated data.

In the constitution of FIG. 1, additional data is input to theadditional data error correction coding unit 105 to be subjected to acoding process of adding an error correction code to the additionaldata. Incidentally, additional data is data formed by variousinformation such as encryption key information, encryption keygenerating information, content reproduction control information,content copy control information, and other content attributeinformation.

The DC control bit specifying means 110 is supplied with a bit string ofthe additional data to which the error correcting code is added. The bitstring is a data string of [0, 0, 0, 1, 0, 0, 0, 0 . . . ], for example.This bit string includes for example the additional data of eitherencryption key information, encryption key generating information,content reproduction control information, content copy controlinformation, or other content attribute information, and the errorcorrecting code added to the additional data.

The additional data recording area controlling unit 107 determineswhether a recording frame is an area for setting an additionalinformation bit on the basis of output data from the main data errorcorrection coding unit 106. When the recording frame is an area forsetting an additional information bit, the additional data recordingarea controlling unit 107 turns on the switch 108 to output DC controlbit information determined by the DC control bit specifying means 110 onthe basis of additional information to the modulated data generatingunit 109. The modulated data generating unit 109 determines and sets thevalue of a DC control bit to be added to the recording framecorresponding to an additional data recording area according to theinstruction from the DC control bit specifying means 110.

The DC control bit specifying means 110 is supplied with the data statevalue, for example parity of main data corresponding to the area forsetting the additional information bit from the modulated datagenerating unit 109. The DC control bit specifying means 110 determinesthe value of the DC control bit on the basis of the value of the parityof the main data and the value of a constituent bit of additional datato be set.

Details of processing performed by the DC control bit specifying means110 will be described with reference to FIGS. 6A, 6B, and 6C and FIGS.7A, 7B, and 7C.

FIGS. 6A, 6B, and 6C represent an example of setting when a constituentbit of additional data is [0]. FIG. 6(1) represents an example when aconstituent bit of additional data is [0] and the parity of main datastored in an additional data setting area (recording frame) is evenparity. FIG. 6(2) represents an example when a constituent bit ofadditional data is [0] and the parity of main data stored in anadditional data setting area (recording frame) is odd parity.

Incidentally, even parity in a data area corresponds to a cumulativevalue of the number of bits 1 included in data included in the data areabeing an even number. Odd parity in a data area corresponds to acumulative value of the number of 1s included in data included in thedata area being an odd number.

It is to be noted that while an example shown in the following usesparity information as state value of a data area including an additionaldata inserting position, various other detectable state values areapplicable as state value of a data area.

In the case of FIG. 6(1), that is, when a constituent bit of additionaldata is [0] and the parity of main data stored in an additional datasetting area (recording frame) is even parity as shown in (a) of FIG. 6,the total parity of DC control bits inserted in the recording frameshown in (b) of FIG. 6 is adjusted to be even parity. A process for thisadjustment is performed by the DC control bit specifying means 110.

Consequently, the total parity of a data part of a modulated recordingframe shown in (c) of FIG. 6 which frame is generated by RLL (1, 7)modulation on the basis of the recording frame is set to even parity.

Incidentally, RLL (1, 7) modulation has a parity preservingcharacteristic, that is, has a characteristic in that modulated data ofeven parity data has even parity, and modulated data of odd parity datahas odd parity.

Hence, in a case of additional data “00001111”, for example, when afirst bit on a MSB side is to be embedded in modulated data, andmodulated data bit pattern parity (the number of 1s) in a specificrecording frame unit is odd parity, the parity of the specific recordingframe unit can be set to even parity by changing one of DC control bitsfrom [0] to [1] or from [1] to [0], and performing a modulating process.Thus the [0] of the additional data can be assigned.

Conversely, when the parity of the specific recording frame unit is oddparity, [1] of the additional data can be assigned. Thus, by assigningdata to the parity of a modulated data bit pattern in an arbitraryspecific recording frame unit, it is possible to record additional datathat does not appear in normal demodulated data.

A reproducing device detects the total parity of the data part of themodulated recording frame, and determines that a constituent bit ofadditional data stored in the recording frame is [0] on the basis of adetermination that the total parity of the data part of the modulatedrecording frame is even parity. Incidentally, details of an additionalbit determining process in a reproducing process will be describedlater.

FIG. 6(2) represents an example when a constituent bit of additionaldata is [0] and the parity of main data stored in an additional datasetting area (recording frame) is odd parity. The total parity of DCcontrol bits inserted in the recording frame shown in (b) of FIG. 6 isadjusted to be odd parity. A process for this adjustment is performed bythe DC control bit specifying means 110.

Consequently, the total parity of a data part of a modulated recordingframe shown in (c) of FIG. 6 which frame is generated by RLL (1, 7)modulation on the basis of the recording frame is set to even parity.

A reproducing device detects the total parity of the data part of themodulated recording frame, and determines that a constituent bit ofadditional data stored in the recording frame is [0] on the basis of adetermination that the total parity of the data part of the modulatedrecording frame is even parity.

(a), (b), and (c) of FIG. 7 represent an example of setting when aconstituent bit of additional data is [1]. FIG. 7(3) represents anexample when a constituent bit of additional data is [1] and the parityof main data stored in an additional data setting area (recording frame)is even parity. FIG. 7(4) represents an example when a constituent bitof additional data is [1] and the parity of main data stored in anadditional data setting area (recording frame) is odd parity.

In the case of FIG. 7(3), that is, when a constituent bit of additionaldata is [1] and the parity of main data stored in an additional datasetting area (recording frame) is even parity, the total parity of DCcontrol bits inserted in the recording frame shown in (b) of FIG. 6 isadjusted to be odd parity. A process for this adjustment is performed bythe DC control bit specifying means 110.

Consequently, the total parity of a data part of a modulated recordingframe shown in (c) of FIG. 6 which frame is generated by RLL (1, 7)modulation on the basis of the recording frame is set to odd parity.

A reproducing device detects the total parity of the data part of themodulated recording frame, and determines that a constituent bit ofadditional data stored in the recording frame is [1] on the basis of adetermination that the total parity of the data part of the modulatedrecording frame is odd parity.

FIG. 7(4) represents an example when a constituent bit of additionaldata is [1] and the parity of main data stored in an additional datasetting area (recording frame) is odd parity. The total parity of DCcontrol bits inserted in the recording frame shown in (b) of FIG. 6 isadjusted to be even parity. A process for this adjustment is performedby the DC control bit specifying means 110.

Consequently, the total parity of a data part of a modulated recordingframe shown in (c) of FIG. 6 which frame is generated by RLL (1, 7)modulation on the basis of the recording frame is set to odd parity.

A reproducing device detects the total parity of the data part of themodulated recording frame, and determines that a constituent bit ofadditional data stored in the recording frame is [1] on the basis of adetermination that the total parity of the data part of the modulatedrecording frame is odd parity.

FIG. 8 is a table summarizing a rule for embedding DC control bitscorresponding to additional data in the present invention.

FIG. 8 shows four patterns (1) to (4) described with reference to (a),(b), and (c) of FIG. 6 and (a), (b), and (c) of FIG. 7.

The pattern (1) represents a case where a constituent bit of additionaldata is [0] and the parity of main data stored in an additional datasetting area (recording frame) is even parity. In this case, the totalparity of DC control bits is set to be even parity. As a result of thissetting, total parity corresponding to all data of a modulated recordingframe in which the DC control bits are set is even parity. Thus, theeven parity is detected by parity detection performed in a reproducingdevice at a time of reproduction, whereby data as an additional dataconstituent bit=0 can be obtained.

FIG. 8(2) represents a case where a constituent bit of additional datais [0] and the parity of main data stored in an additional data settingarea (recording frame) is odd parity. In this case, the total parity ofDC control bits is set to be odd parity. As a result of this setting,total parity corresponding to all data of a modulated recording frame inwhich the DC control bits are set is even parity. Thus, the even parityis detected by parity detection performed in a reproducing device at atime of reproduction, whereby data as an additional data constituentbit=0 can be obtained.

FIG. 8(3) represents a case where a constituent bit of additional datais [1] and the parity of main data stored in an additional data settingarea (recording frame) is even parity. In this case, the total parity ofDC control bits is set to be odd parity. As a result of this setting,total parity corresponding to all data of a modulated recording frame inwhich the DC control bits are set is odd parity. Thus, the odd parity isdetected by parity detection performed in a reproducing device at a timeof reproduction, whereby data as an additional data constituent bit=1can be obtained.

FIG. 8(4) represents a case where a constituent bit of additional datais [1] and the parity of main data stored in an additional data settingarea (recording frame) is odd parity. In this case, the total parity ofDC control bits is set to be even parity. As a result of this setting,total parity corresponding to all data of a modulated recording frame inwhich the DC control bits are set is odd parity. Thus, the odd parity isdetected by parity detection performed in a reproducing device at a timeof reproduction, whereby data as an additional data constituent bit=1can be obtained.

The sequence of an additional data recording process performed by the DCcontrol bit specifying means 110 in the information recording processingdevice according to the present invention will next be described withreference to FIG. 9.

In step S101, additional data after error correction coding is input.This data is output from the additional data error correction codingunit 105 shown in FIG. 1. The data is formed by various information suchas encryption key information, encryption key generating information,content reproduction control information, content copy controlinformation, and other content attribute information. A bit string ofthe additional data to which an error correcting code is added, forexample a data string [0, 0, 0, 1, 0, 0, 0 . . . ] or the like is inputto the DC control bit specifying means 110.

In step S102, one bit is extracted as a recording bit in order from theconstituent bits, for example, [0, 0, 0, 1, 0, 0, 0 . . . ] of theadditional data. In step S103, whether the recording bit is [0] isdetermined.

When the recording bit is [0], the process proceeds to step S104. Whenthe recording bit is [1], the process proceeds to step S105.

When the recording bit is [0], the parity of main data in a data area inwhich to store additional data is determined in step S104. When theparity of the main data is even parity, the process proceeds to stepS106, where the total parity of DC control bits is set to even parity,and then a modulating process is performed. As a result, the totalparity of modulated data is set to even parity. This process correspondsto a process for (b) and (c) in FIG. 6(1).

When it is determined in step S104 that the parity of the main data inthe data area in which to store the additional data is odd parity, theprocess proceeds to step S107, where the total parity of the DC controlbits is set to odd parity, and then a modulating process is performed.As a result, the total parity of modulated data is set to even parity.This process corresponds to a process for (b) and (c) in FIG. 6(2).

When the recording bit is [1], the parity of the main data in the dataarea in which to store the additional data is determined in step S105.When the parity of the main data is even parity, the process proceeds tostep S107, where the total parity of the DC control bits is set to oddparity, and then a modulating process is performed. As a result, thetotal parity of modulated data is set to odd parity. This processcorresponds to a process for (b) and (c) in FIG. 7(3).

When it is determined in step S105 that the parity of the main data inthe data area in which to store the additional data is odd parity, theprocess proceeds to step S106, where the total parity of the DC controlbits is set to even parity, and then a modulating process is performed.As a result, the total parity of modulated data is set to odd parity.This process corresponds to a process for (b) and (c) in FIG. 7(4).

In step S108, it is determined whether processing of a last bit of theadditional data is completed. When there is unprocessed data, theprocess from step S102 on down is repeated.

When it is determined in step S108 that there is no unprocessed data,the process is ended, that is, recording data having additionalinformation bits inserted therein is generated according to theabove-described process.

Description will next be made of a configuration and a reproducingprocess sequence of a data reproduction processing device thatreproduces an information recording medium storing the above-describedadditional information and contents (main data) such as a movie, musicor the like.

The configuration and processing of the data reproduction processingdevice will be described with reference to FIG. 10. The datareproduction processing device includes: an information recording medium401; a pickup 402 for reading data from the information recording medium401; a spindle motor 403 for driving the information recording medium401; a servo circuit 404 for controlling the pickup 402 and the spindlemotor 403; an RF circuit unit 405 for performing signal processing suchas gain adjustment of a read signal and the like, and generating an RFsignal; a synchronism detecting unit 406 for extracting a synchronizingsignal from the RF signal; a data demodulation processing unit 407 forperforming data demodulation processing; a switch 410 for outputting asignal read only from an area of additional data on the informationrecording medium to an additional data decoding unit 408; an additionaldata-recorded area detecting unit 411 for detecting the area of theadditional data and controlling the switch 410; the additional datadecoding unit 408 for decoding the additional data; a main data errorcorrecting unit 412 for performing error correction processing on maindata; and an additional data error correcting unit 409 for performingerror correction processing on the additional data.

Content data stored on the information recording medium 401 is encryptedcontent data, for example. The additional data stored on the informationrecording medium 401 is for example key data applied to the decryptionof encrypted contents, key generating information, content reproductioncontrol information, content copy control information, and other contentattribute information.

Data read from the information recording medium 401 via the pickup 402is subjected to signal processing such as gain adjustment and the likein the RF circuit unit 405, and then input to the synchronism detectingunit 406. The synchronism detecting unit 406 detects a synchronizingsignal (sync) in the recorded signal. The synchronism detecting unit 406outputs the detected signal to the additional data-recorded areacontrolling unit 411. The additional data-recorded area controlling unit411 determines an additional data recording area on the basis of thesynchronizing signal input from the synchronism detecting unit 406. Theadditional data-recorded area detecting unit 411 controls the switch 410on the basis of information on the determination to input modulated dataof the area necessary to decode additional data to the additional datadecoding unit 408, which decodes the additional data.

On the basis of the input modulated data, the additional data decodingunit 408 performs a decoding process to obtain the additional data.Specifically, the additional data decoding unit 408 detects a data statevalue (parity) in a predetermined modulated data area including anadditional data storing area, and determines whether the constituent bitof the additional data is [0] or [1] on the basis of the detected statevalue.

That is, the additional data decoding unit 408 calculates the totalparity of a data part of a recording frame in which the additional datais set. When the total parity is even parity, the additional datadecoding unit 408 determines that the constituent bit of the additionaldata=[0]. When the total parity is even parity, the additional datadecoding unit 408 determines that the constituent bit of the additionaldata=[1].

Thus, in the reproducing device, in the case of a frame havingadditional data stored in data to be demodulated which data is input tothe data demodulation processing unit 407, the data of the frame isinput to the additional data decoding unit 408 via the switch 410.Whether the additional information bit is [0] or [1] can be determinedby only calculating the total parity of the data area in the additionaldata decoding unit 408.

The additional data decoding unit 408 performs similar processing on themodulated data of areas necessary to decode intermittently inputadditional data. The additional data decoding unit 408 thereby obtainsthe additional data such for example as key data as n-bit information,key generating information, content reproduction control information,content copy control information, or other content attributeinformation. Incidentally, this additional data includes an errorcorrecting code as mentioned in the description of the data recordingprocessing device. The additional data is subjected to error correctionin the additional data error correcting unit 409, and then output.

Incidentally, when the additional data is key information applied to thedecryption of contents, for example, the additional data is output to adecryption processing unit that decrypts the contents. When theadditional data is content reproduction control information, theadditional data is output to a reproduction controlling unit.

As for general data other than the additional data, the data read fromthe information recording medium is output from the synchronismdetecting unit 406 to the data demodulation processing unit 407. Dataconversions reverse to those described above with reference to FIGS. 2Ato 3H are sequentially performed, whereby reproduced data is obtained.

As with the additional data, main data as demodulated data includes anerror correcting code. The main data is subjected to error correction inthe main data error correcting unit 412, and then output.

Incidentally, when the output data is encrypted contents, for example,the output data is subjected to a decrypting process applying anencryption key that can be generated on the basis of key generatinginformation output as the additional data, and then output viaoutputting means such as a display, a speaker and the like.

A reproduction process sequence including additional information readingwill next be described with reference to FIG. 11. The process of FIG. 11is performed in the reproduction processing device shown in FIG. 10.

In step S201, an RF signal is generated on the basis of a signal readfrom the information recording medium. In step S202, demodulationprocessing is performed on the RF signal, and the parity of a modulatedrecording frame corresponding to an additional data storing area iscalculated. The total parity of the modulated recording frame shown in(c) of FIG. 6 and (c) of FIG. 7 is calculated.

In step S203, it is determined whether the total parity of the modulatedrecording frame is even parity. When the total parity of the modulatedrecording frame is even parity, it is determined in step S204 that anadditional data bit=0. When the total parity of the modulated recordingframe is odd parity, it is determined in step S205 that the additionaldata bit=1.

In step S206, it is determined whether the additional data bit is a lastbit of additional data. When there is an unprocessed bit, the processfrom step S202 on down is repeated. When the last bit of the additionaldata is processed, the process is ended.

It is to be noted that while the foregoing embodiment has been describedcentering on an example using parity information, parity is an exampleof state information of a data area, and various other detectable statevalues are applicable. That is, various information other than parity isapplicable as long as the information represents a state obtained fromdata.

In addition, in the above-described embodiment, additional datainformation is set by setting the parity of user control data (UCD) toeven parity or odd parity, the present invention is not limited to usercontrol data (UCD). When there is a bit-adjustable area in another dataarea, the data area may be set as additional data-corresponding data tobe controlled at a time of writing and to be decoded at a time of datareading.

The present invention has been explained above in detail with referenceto a specific embodiment thereof. It is obvious, however, thatmodifications and substitutions in the embodiment may be made by thoseskilled in the art without departing from the spirit of the presentinvention. That is, the present invention has been disclosed in a formthat is illustrative and is thus not to be construed in a restrictivemanner. In order to determine the spirit of the present invention, asection of claims described at the beginning hereof is to be considered.

Incidentally, the series of processes described in the specification canbe carried out by hardware or by software or by a compositeconfiguration of both. When the processes are to be carried out bysoftware, a program in which process sequences are recorded can beinstalled into a memory within a computer incorporated in specialhardware, and then executed, or installed onto a general-purposecomputer capable of performing various processing, and then executed.

For example, the program can be recorded in advance on a hard disk or ina ROM (Read Only Memory) as a recording medium. Alternatively, theprogram can be stored (recorded) temporarily or permanently on aremovable recording medium such as a flexible disk, a CD-ROM (CompactDisc Read Only Memory), an MO (Magneto Optical) disk, a DVD (DigitalVersatile Disc), a magnetic disk, a semiconductor memory or the like.Such removable recording media can be provided as so-called packagedsoftware.

In addition to being installed onto a computer from a removablerecording medium as described above, the program can be transferred byradio from a download site to a computer or transferred to a computer bywire via a network such as a LAN (Local Area Network), the Internet orthe like. The computer can receive the program thus transferred thereto,and install the program onto a recording medium such as a built-in harddisk or the like.

It is to be noted that the various processes described in thespecification may be carried out not only in time series according tothe description but also in parallel or individually according toprocessing capability of an apparatus performing the processes or asrequired. In the present specification, a system refers to a logical setconfiguration of a plurality of devices, and each constituent device isnot necessarily present within an identical casing.

INDUSTRIAL APPLICABILITY

As described above, according to a constitution of the presentinvention, when additional data is recorded onto an informationrecording medium, or additional information such for example as keyinformation applied to a content decrypting process, key generatinginformation, content reproduction control information, or copy controlinformation is recorded onto the information recording medium, the valueof a DC control bit embedded in a recording frame is determined and setaccording to the data state of an additional data recording area andconstituent bit information [0] or [1] of the additional data. At a timeof reproduction, the additional constituent bit information [0] or [1]can be obtained by detecting the data state of constituent data of therecording frame. Thus, the present invention is applicable to aninformation recording processing device, an information reproductionprocessing device, and an information recording medium when it isnecessary, for example, to store contents whose copyright needs to beprotected on a recording medium and embed additional information such askey information applied to a process of decrypting the contents, keygenerating information, content reproduction control information, copycontrol information or the like in a mode difficult to analyze.

According to a constitution of the present invention, in a process ofrecording additional data, for example, it is possible to record aconstituent bit [0] or [1] of the additional data by only calculatingthe parity value of data of a recording frame in which to insert theadditional data, and determining and setting the value of a DC controlbit in the frame in which to store the additional data on the basis ofinformation indicating whether the parity of the data of the recordingframe is even parity or odd parity and the bit value information [0] or[1] of the additional data. At a time of reproduction, additionalinformation can be obtained by only detecting the parity of read data.Thus, the present invention is applicable to an information recordingprocessing device, an information reproduction processing device, and aninformation recording medium when it is necessary, for example, to storecontents whose copyright needs to be protected on a recording medium andembed additional information such as key information applied to aprocess of decrypting the contents, key generating information, contentreproduction control information, copy control information or the likein a mode difficult to analyze.

1. An information recording processing device comprising: a modulateddata generating unit for generating a modulated recording frame bysetting a DC control bit in data to be recorded and performing datamodulation processing; and a DC control bit specifying unit fordetermining a bit value of the DC control bit set in a recording framein which to store additional data on a basis of a constituent bit valueof the additional data and a data state of constituent data of therecording frame.
 2. The information recording processing device asclaimed in claim 1, wherein the data state of the constituent data ofthe recording frame in which to store said additional data is a state ofwhether parity of the constituent data of the recording frame is evenparity or odd parity, and said DC control bit specifying unit determinesthe bit value of the DC control bit set in the recording frame on abasis of two conditions of whether the constituent bit value of saidadditional data is zero or one and whether the parity of the constituentdata of the recording frame is even parity or odd parity.
 3. Theinformation recording processing device as claimed in claim 1, whereinsaid DC control bit specifying unit determines whether to set totalparity of all DC control bits set in the recording frame in which tostore said additional data to even parity or to odd parity on a basis ofthe constituent bit value of the additional data and the data state ofthe constituent data of the recording frame in which to store theadditional data.
 4. The information recording processing device asclaimed in claim 1, wherein said information recording processing devicesets said additional data as constituent information of at least one ofencryption key information, encryption key generating information,content reproduction control information, and content copy controlinformation for contents stored on said information recording medium. 5.The information recording processing device as claimed in claim 1,wherein said modulated data generating unit generates the modulatedrecording frame by performing a data conversion process satisfying RLL(1, 7) as a run length rule.
 6. The information recording processingdevice as claimed in claim 1, wherein said modulated data generatingunit performs a modulated recording frame generating process including aprocess of conversion of two-bit information into three-bit information.7. An information reproduction processing device for reproducinginformation stored on an information recording medium, said informationreproduction processing device comprising: a demodulating unit fordemodulating data read from the information recording medium; and anadditional data decoding unit for calculating a state of recorded data,and obtaining constituent bit information of additional data as recordedinformation stored in an additional data recording area on a basis of aresult of calculating the state.
 8. The information reproductionprocessing device as claimed in claim 7, wherein the state of therecorded data, said state being calculated by said additional datadecoding unit, is parity of constituent data of a modulated recordingframe corresponding to the additional data recording area, and whether aconstituent bit value of said additional data is zero or one isdetermined on a basis of the state of whether the parity is even parityor odd parity.
 9. The information reproduction processing device asclaimed in claim 7, wherein at least one of encryption key information,encryption key generating information, content reproduction controlinformation, and content copy control information for contents stored onsaid information recording medium is generated on a basis of theobtained constituent bit information of the additional data.
 10. Aninformation recording medium wherein a recording frame corresponding toan additional data recording area is a recording frame in which a DCcontrol bit having a bit value determined on a basis of two conditionsof a constituent bit value of additional data and whether parity ofconstituent data of the recording frame is even parity or odd parity isset, and data based on the recording frame is recorded on theinformation recording medium.
 11. The information recording medium asclaimed in claim 10, wherein the recording frame corresponding to saidadditional data recording area is recorded with total parity of DCcontrol bits set to one of even parity and odd parity according to apredetermined rule on a basis of a correspondence between theconstituent bit value of the additional data and a data state of theconstituent data of the recording frame in which to store the additionaldata.
 12. The information recording medium as claimed in claim 10,wherein said additional data is stored as constituent information of atleast one of encryption key information, encryption key generatinginformation, content reproduction control information, and content copycontrol information for contents stored on said information recordingmedium.
 13. The information recording medium as claimed in claim 10,wherein the data based on a modulated recording frame generated byperforming a data conversion process satisfying RLL (1, 7) as a runlength rule is recorded.
 14. The information recording medium as claimedin claim 10, wherein the data based on a modulated recording framegenerated by performing a process of converting two-bit information intothree-bit information is recorded.
 15. An information recordingprocessing method comprising: a DC control bit specifying step ofdetermining a bit value of a DC control bit set in a recording frame inwhich to store additional data on a basis of a constituent bit value ofthe additional data and a data state of constituent data of therecording frame; and a modulated data generating step of generating amodulated recording frame by setting the DC control bit specified insaid DC control bit specifying step in data to be recorded andperforming data modulation processing.
 16. The information recordingprocessing method as claimed in claim 15, wherein the data state of theconstituent data of the recording frame in which to store saidadditional data is a state of whether parity of the constituent data ofthe recording frame is even parity or odd parity, and said DC controlbit specifying step includes a step of determining the bit value of theDC control bit set in the recording frame on a basis of two conditionsof whether the constituent bit value of said additional data is zero orone and whether the parity of the constituent data of the recordingframe is even parity or odd parity.
 17. The information recordingprocessing method as claimed in claim 15, wherein said DC control bitspecifying step includes a step of determining whether to set totalparity of all DC control bits set in the recording frame in which tostore said additional data to even parity or to odd parity on a basis ofthe constituent bit value of the additional data and the data state ofthe constituent data of the recording frame in which to store theadditional data.
 18. The information recording processing method asclaimed in claim 15, wherein said additional data is constituentinformation of at least one of encryption key information, encryptionkey generating information, content reproduction control information,and content copy control information for contents stored on saidinformation recording medium.
 19. The information recording processingmethod as claimed in claim 15, wherein said modulated data generatingstep generates the modulated recording frame by performing a dataconversion process satisfying RLL (1, 7) as a run length rule.
 20. Theinformation recording processing method as claimed in claim 15, whereinsaid modulated data generating step performs a modulated recording framegenerating process including a process of conversion of two-bitinformation into three-bit information.
 21. An information reproductionprocessing method for reproducing information stored on an informationrecording medium, said information reproduction processing methodcomprising: a demodulating step of demodulating data read from theinformation recording medium; and an additional data decoding step ofcalculating a state of recorded data, and obtaining constituent bitinformation of additional data as recorded information stored in anadditional data recording area on a basis of a result of calculating thestate.
 22. The information reproduction processing method as claimed inclaim 21, wherein said additional data decoding step includes a step ofcalculating parity of constituent data of a modulated recording framecorresponding to the additional data recording area as the state of saidrecorded data, and determining whether a constituent bit value of saidadditional data is zero or one on a basis of the state of whether theparity is even parity or odd parity.
 23. The information reproductionprocessing method as claimed in claim 21, wherein said informationreproduction processing method further includes a step of generating atleast one of encryption key information, encryption key generatinginformation, content reproduction control information, and content copycontrol information for contents stored on said information recordingmedium on a basis of the obtained constituent bit information of theadditional data.
 24. A computer program for performing an informationrecording process, said computer program comprising: a DC control bitspecifying step of determining a bit value of a DC control bit set in arecording frame in which to store additional data on a basis of aconstituent bit value of the additional data and a data state ofconstituent data of the recording frame; and a modulated data generatingstep of generating a modulated recording frame by setting the DC controlbit specified in said DC control bit specifying step in data to berecorded and performing data modulation processing.
 25. A computerprogram for reproducing information stored on an information recordingmedium, said computer program comprising: a demodulating step ofdemodulating data read from the information recording medium; and anadditional data decoding step of calculating a state of recorded data,and obtaining constituent bit information of additional data as recordedinformation stored in an additional data recording area on a basis of aresult of calculating the state.